Adjustable gastric banding apparatus have provided an effective and substantially less invasive alternative to gastric bypass surgery and other conventional surgical weight loss procedures. Despite the positive outcomes of invasive weight loss procedures, such as gastric bypass surgery, it has been recognized that sustained weight loss can be achieved through a laparoscopically-placed gastric band, for example, the LAP-BAND® (Allergan, Inc., Irvine, Calif.) gastric band or the LAP-BAND AP® (Allergan, Inc., Irvine, Calif.) gastric band. Generally, gastric bands are placed about the cardia, or upper portion, of a patient's stomach forming a stoma that restricts the food's passage into a lower portion of the stomach. When the stoma is of an appropriate size that is restricted by a gastric band, the food held in the upper portion of the stomach provides a feeling of satiety or fullness that discourages overeating. Unlike gastric bypass procedures, gastric band apparatus are reversible and require no permanent modification to the gastrointestinal tract.
Over time, a stoma created by a gastric band may need adjustment in order to maintain an appropriate size, which is neither too restrictive nor too passive. Accordingly, prior art gastric band systems provide a subcutaneous fluid access port connected to an expandable or inflatable portion of the gastric band. By adding fluid to or removing fluid from the inflatable portion by means of a hypodermic needle inserted into the access port, the effective size of the gastric band can be adjusted to provide a tighter or looser constriction.
Non-invasive adjustment systems and methods have also been proposed to change the constriction of a gastric band, for example, without the use of a hypodermic needle. Some of these systems utilize implantable pumps to perform the constriction changes. However, the system specifications for these pumps, such as small size, power dissipation, flow rate, back pressure, and magnetic resonance imaging, result in challenging constraints for pump implementation.
Furthermore, some non-invasive systems that utilize pumps may generate excessive heat, such that tissue surrounding the implanted device may be heated more than is desirable. The amount of power utilized to drive the pump may contribute to the excess heating.
Additionally, some body-related systems utilize temperature measurements. For example, Grandjean, U.S. Pat. No. 5,089,019, generally discloses a muscle work output monitor that uses intramuscular temperature variation measurements. However, Grandjean does not disclose controlling operation of an implantable device based on the temperature associated with the implantable device.
Klicek, U.S. Pat. No. 5,496,312, generally discloses a control that responds to impedance and temperature between active and return electrodes of an electrosurgical generator during tissue desiccation. However, Klicek does not disclose utilizing temperature measurements to regulate the fluid flow and/or pressure within an implantable device.
Davis, et al., U.S. Pat. No. 6,681,135, generally discloses a pacemaker that is operational based on temperature. Similarly, Salo, U.S. Pat. No. 7,206,637, discloses cardiac pacing using sensed coronary vein blood temperature. And Armstrong, U.S. Pat. No. 7,366,571, discloses a neurostimulator with activation based on changes in body temperature. But Davis, Salo, and Armstrong do not disclose determining and/or inferring a temperature of an implantable component to control operation of an implantable gastric band.
Thus, there continues to remain a need for more effective implantable pump systems for use with adjustable gastric bands, particularly such implantable pump systems with pumping capability that achieves the desired flow rate within other design parameters such as voltage and temperature.
Further, there is a need for more effective implantable pump systems for adjustable gastric bands that are more efficient and are capable of monitoring various implantable system parameters in order to achieve a higher operational efficiency and to ensure operation within desired parameters.